Image reading apparatus

ABSTRACT

This invention has as its object to provide a highly reliable image reading apparatus in which both an image reading unit and photographing unit can obtain optimal images. To achieve this object, the apparatus has a light-emitting element array which illuminates a document to be read by a read sensor, and an illumination lamp which illuminates the document to be recorded by the photographing unit.

FIELD OF THE INVENTION

[0001] The present invention relates to an image reading apparatus whichcomprises an image reading unit for reading an image of a document, anda photographing unit for recording an image on a photosensitive membersuch as a film by exposure.

BACKGROUND OF THE INVENTION

[0002] In general, an image reading apparatus (to be referred to as a“document scanner” hereinafter) for reading an image as digital imageinformation using a photoelectric conversion element allows easy search,edit, and the like of read and stored information. However, the storedinformation is not legally endorsed. For example, the stored informationcannot be used as an evidence in court. On the other hand, a microfilmon which an image is recorded by the microfilm photographing apparatusis legally endorsed. However, stored information does not allow easysearch, edit, and the like.

[0003] In this way, the document scanner and microfilm photographingapparatus have opposite characteristics. Hence, an image readingapparatus which can utilize merits of both the microfilm photographingapparatus and document scanner by combining the photographing functionof the microfilm photographing apparatus and the function of thedocument scanner may be proposed. That is, an image reading apparatuswhich allows easy search, edit, and the like of stored information, andcan store information to be legally endorsed may be proposed.

[0004] A microfilm photographing apparatus (also called a rotarymicrofilm camera) for photographing an image on a document on a rollfilm by slit exposure while feeding the document at a constant speed isknown. Also, an image reading apparatus for reading an image on adocument by inputting it to a fixed photoelectric conversion element asa linear image while feeding the document is known. Note that thedocument includes not only a sheet but also thin media such as a card,label, and the like which bear images such as text, pictures, and thelike.

[0005]FIG. 2 is a schematic view showing principal part of aconventional image reading apparatus.

[0006] Referring to FIG. 2, reference numeral 201 denotes a documentserving as an object; 202A and 202B, transparent guide glass windowsprovided on a convey path to photograph the conveyed document 201; 203Aand 203B, lamps for illuminating the document to project an image onto alight-receiving element that performs photoelectric conversion or amicrofilm; 204A and 204B, first mirrors which form an optical path forprojecting the image of the illuminated document onto thelight-receiving element and microfilm; and 205, a slit for splitting theoptical path of the image illuminated with lamps into thelight-receiving element side and the microfilm photographing side.

[0007] Reference numeral 206 denotes a second mirror for guiding theoptical path split by the slit 205 toward the light-receiving element;207, a third mirror for guiding the optical path split by the slit 205toward the microfilm side; and 208 and 209, fourth and fifth mirrors forsimilarly guiding the optical path toward the microfilm.

[0008] Reference numeral 210 denotes a lens for projecting the imageonto the light-receiving element; 211, a read sensor having aphotoelectric conversion light-receiving element; 212, a microfilm lensfor projecting the image onto the microfilm; 213, a microfilm; and 214,a light amount varying unit prepared by combining two polarizationplates to adjust the amount of light to be projected onto thelight-receiving element. In the light amount varying unit, the twopolarization plates are arranged to overlap each other, and are pivotedso that their directions of polarization cross, thereby adjusting thetransmission light amount.

[0009] The overall operation will be explained first. A document 201 isconveyed by a document convey unit (not shown) to the guide glasswindows. When the conveyed document has reached an image photographingarea inside the guide glass windows 202, it is illuminated by the lamps203A and 203B. An image on the illuminated document is guided toward thephotographing side via the first mirrors 204A and 204B, and its opticalpath is split into the read sensor side and microfilm photographing sideby the slit 205 inserted between the first mirrors 204A and 204B, andthe second and third mirrors 206 and 207.

[0010] Of the split optical paths, the image guided toward the readsensor side is projected onto and read by the read sensor by the lens210 via the second mirror 206. The image read by the read sensor iscaptured as image data into a main body (not shown).

[0011] The other optical path split by the slit is guided to the third,fourth, and fifth mirrors 207, 208, and 209, and the microfilm 213 isexposed with the illuminated image via the microfilm lens 212.

[0012] Read by the read sensor and photographing on the microfilm aredone using identical light source light, as can be seen from thearrangement of the optical path.

[0013] However, in the aforementioned prior art, since a document isilluminated using a single light source, wavelength ranges and lightamounts respectively suitable for the light-receiving element thatperforms photoelectric conversion, and a photosensitive material such asa microfilm or the like cannot be selected. FIG. 6 shows an example ofthe characteristics of the photosensitive material and light-receivingelements depending on the light amount.

[0014] As can be seen from FIG. 6, when an exposure value is set toobtain an image having an appropriate density upon microfilmphotographing, an appropriate image can be photographed on themicrofilm. However, that exposure value results in an excessive lightamount on the light-receiving element that performs photoelectricconversion, and the read image suffers fog and blurred text, resultingin poor reproduction of details.

[0015] Hence, the light amount varying unit such as a filter or the likedescribed in the prior art is required on the optical path between theslit and light-receiving element so as to obtain an appropriate lightamount on the light-receiving element. However, such unit maydeteriorate image quality. Furthermore, as can be seen from FIG. 3, thelight-receiving element that performs photoelectric conversion, andphotosensitive material have different photosensitive characteristics.

[0016] As can be seen from the above description, when a single lightsource is used, it is very troublesome to adjust light source light tothe photosensitive characteristics of both the light-receiving elementand photosensitive material so as to obtain an optimal image, resultingin an expensive apparatus.

[0017] In order to allow density adjustment on the photoelectricallyconverted image side, the light amount varying unit described in theprior art is required, resulting in a complicated mechanism.

[0018] In addition, the density of the photographed image on themicrofilm changes depending on the image density of the document uponphotographing and the characteristics of a developing machine. In thiscase, the exposure value must be adjusted.

[0019] Likewise, density adjustment of the light-receiving element thatperforms photoelectric conversion is required in correspondence with animage on a document so as to read an image with higher quality.

[0020] Since the “exposure value—density output characteristics” of thelight-receiving element and microfilm have no correlation, they must beindividually set.

[0021] An image reading apparatus normally has a plurality of readresolutions, and changes the document convey speed in correspondencewith the read resolution so as to take balance between the image qualityand file size of the read image. Upon reading at high resolution, if theread speed per line is to be increased while setting a constant documentspeed, a high-speed, high-sensitivity photoelectric conversion element,and also a higher-speed image processing circuit are required, resultingin an expensive, complicated arrangement. Hence, the image readingapparatus changes and sets the document convey speed in correspondencewith the read processing speed of a read processor while taking balancebetween the cost and arrangement. In this case, in the photographingapparatus using a photosensitive material such as a microfilm or thelike, the amount of illumination light must be changed in correspondencewith the convey speed for keeping the density of the photographed imageconstant, because the density of the image is defined by the amount ofillumination light and an exposed time.

[0022] However, since the conventional apparatus illuminates a documentusing a single light source, setups that can satisfy the image qualitiesof both the photoelectric conversion side and film side cannot beobtained, because the changeable amount of the illumination light amountis limited.

[0023] In the conventional microfilm photographing apparatus, the feedspeed of the document is always constant, and the photographingreduction factor can be switched within the range from ({fraction(1/24)}) to ({fraction (1/57)}). For this reason, the user prepares aplurality of photographing lenses having different reduction factors,and exchanges photographing lenses in accordance with the requiredreduction factor. The microfilm photographing apparatus changes the feedspeed of the film in correspondence with the reduction factor, and takesa photo while the exposure value remains the same.

[0024] Also, the microfilm photographing device changes the brightnessof illumination of a document since the developing condition of thephotographed film, the density of the document, and the like may vary.For this purpose, the conventional microfilm photographing apparatus canadjust the brightness of a lamp that illuminates a document within therange from about 10% to about 50%. For example, the microfilmphotographing apparatus adjusts the brightness of the lamp thatilluminates a document by phase control of an AC power supply of a lampsuch as a bulb, fluorescent lamp, or the like using a thyristor or thelike, DC control for changing a voltage applied to a lamp, PWM controlfor controlling the amount of light of a lamp for turning on/offelectric power applied to the lamp, and the like.

[0025] However, when the image reading apparatus mainly uses thefunction of the microfilm photographing apparatus to improve the readresolution, as a constant exposure value on a microfilm is set, thedocument convey speed can only be changed within the adjustment range ofa lamp regulator that adjusts illumination of a document. For thisreason, the image read resolution of the document scanner in which theread processing speed per line is fixed cannot be drastically changed.

[0026] When the read resolution is improved by mainly using the functionof the document scanner so as not to disturb the performance of thedocument scanner, the following problem is posed.

[0027] The read resolution of the document scanner can be freely set bychanging the document convey speed. For this reason, the documentscanner normally has a read resolution range of about six times or more,i.e., a range from about 100 dots per inch (dpi) to about 600 dpi. Dotsper inch indicate the number of dots per inch.

[0028] In this case, the convey speed of a film as the document changesabout six times in correspondence with the read resolution. In themicrofilm photographing apparatus that takes a photo by slit exposure,if the amount of light of a document illumination lamp is constant, theexposure value of a film increases in inverse proportion to the documentconvey speed, thus disturbing photographing at an appropriate density.

[0029] The document convey speed is added as new change condition, andconventional conditions such as the developing conditions, documentdensity, and the like must also be taken into consideration. Hence, inorder to maintain a constant density of the photographed image inconsideration of all these conditions, the light amount of the documentillumination lamp of the microfilm photographing apparatus must bevaried within the range of around 12 times (around 100% to 8.4%).

[0030] For this reason, a lamp light amount control circuit forcontrolling the amount of light of illumination of a document mustcontrol the amount of light within the range of around 12 times or more.Since the light amount control range of a general circuit is around 10%to 50%, control that largely diverges from the general limit range ofthe amount of light is required, resulting in a very expensive circuit.

[0031] As a method of adjusting the amount of light by a relativelysimple circuit arrangement, a plurality of illumination lamps may beprepared for the obverse and reverse sides of a document, and the amountof light may be controlled by controlling the number of ON illuminationlamps. However, a plurality of illumination lamps, lamp controlcircuits, and the like are required, a size reduction of the apparatuscannot be attained, and the cost is high.

[0032] Therefore, upon simultaneously reading an image using themicrofilm photographing apparatus and document scanner, one of anarrangement which sets a constant image read speed to fix the readresolution, and an arrangement which can change the image read speed,prepares for an expensive document illumination device, and adjusts theamount of light in correspondence with the document convey speed must beselected.

SUMMARY OF THE INVENTION

[0033] The present invention has been made to solve the conventionalproblems and has as its object to provide a highly reliable imagereading apparatus in which both an image reading unit and photographingunit can obtain optimal images.

[0034] It is another object of the present invention to provide an imagereading apparatus which can adjust the amount of light corresponding tothe document convey speed by changing the degree of opening of a sliteven when the document read speed is changed.

[0035] In order to solve the above problems and to achieve the aboveobjects, an image reading apparatus according to the first aspect of thepresent invention is characterized by the following arrangement.

[0036] That is, an image reading apparatus which comprises an imagereading unit which reads image information of a document, and aphotographing unit which records an image of the document on aphotosensitive material by exposure, comprises a first imageillumination unit which illuminates the document read by the imagereading unit, and a second image illumination unit which illuminates thedocument recorded by the photographing unit.

[0037] Also, an image reading apparatus according to the second aspectof the present invention is characterized by the following arrangement.

[0038] That is, an image reading apparatus comprises a document conveyunit which conveys a document, an image reading unit which reads animage on the document conveyed by the document convey unit, a resolutionselection unit which selects an image read resolution of the imagereading unit, a photographing unit which has an exposure adjustment unitwhich adjusts an exposure value by controlling a degree of opening of aslit, and photographs an image on the document conveyed by the documentconvey unit, and a control unit which controls operations of thedocument convey unit and the exposure adjustment unit on the basis ofthe resolution selected by the resolution selection unit so as to adjusta convey speed of the document and the exposure value.

[0039] Other objects and advantages besides those discussed above shallbe apparent to those skilled in the art from the description of apreferred embodiment of the invention which follows. In the description,reference is made to accompanying drawings, which form a part hereof,and which illustrate an example of the invention. Such example, however,is not an exhaustive of the various embodiments of the invention, andtherefore reference is made to the claims which follow the descriptionfor determining the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040]FIG. 1 is a schematic view for explaining an image readingapparatus according to the first embodiment of the present invention;

[0041]FIG. 2 is a schematic view for explaining an example of the priorart;

[0042]FIG. 3 is a graph showing the spectral sensitivity characteristicsof a light-receiving element that performs photoelectric conversion, anda photosensitive material;

[0043]FIG. 4 is a schematic perspective view showing a varying operationof a slit;

[0044]FIG. 5 is a schematic perspective view for explaining principalpart of the image reading apparatus according to the first embodiment;

[0045]FIG. 6 is a graph showing the light amount sensitivitycharacteristics of a light-receiving element that performs photoelectricconversion, and a photosensitive material;

[0046]FIG. 7 is a perspective view showing the layout of a document,image read sensor, lens array, and light-emitting element array;

[0047]FIG. 8 is a schematic front sectional view of an image readingapparatus according to the second embodiment of the present invention;

[0048]FIG. 9 is a schematic perspective view of a microfilmphotographing unit in FIG. 8;

[0049]FIG. 10 is a perspective view of an exposure value adjustment slitmechanism in FIG. 9;

[0050]FIG. 11 shows an optical path for a high document convey speed;

[0051]FIG. 12 shows an optical path for a low document convey speed; and

[0052]FIG. 13 is a schematic perspective view of a microfilmphotographing unit of the third embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] Preferred embodiments of the present invention will be explainedin detail hereinafter with reference to the accompanying drawings. Notethat the dimensions, materials, and shapes of building components, theirrelative layout, and the like described in the embodiments should bechanged as needed depending on the arrangement of an apparatus to whichthe present invention is applied, and various conditions, and do notlimit the scope of the present invention to themselves unless otherwisespecified.

[0054] (First Embodiment)

[0055]FIG. 1 is a schematic view of an image reading apparatus accordingto the first embodiment of the present invention.

[0056] Reference numeral 101 denotes a document serving as an object;102, 103, and 104, a pickup roller, feed roller, and separation rollerfor separating and feeding a stack of documents one by one; 105, conveyrollers for conveying the fed document; 106A and 106B, convey guideplates for guiding the document to be conveyed; 107A and 107B,transparent guide glass windows provided on the convey path to read theconveyed document 101 by light-receiving elements; and 108A and 108B,read sensors as image reading units each having a linear array oflight-receiving elements for performing photoelectric conversion. Thesub-scan direction of the light-receiving element array agrees with thedocument convey direction. Also, by changing the document convey speed,the image read resolution of the light-receiving elements can be set.

[0057] Reference numerals 109A and 109B denote lens arrays which line upin the same direction as the read sensors 108A and 108B and are used toform an image of the conveyed document on the read sensors 108A and108B; and 110A and 110B, light-emitting element arrays which line up inthe same direction as the read sensors 108A and 108B, and serve as afirst image illumination unit for illuminating the document.

[0058] The light-emitting element arrays 110A and 110B can be set aslight sources according to the light-receiving sensitivitycharacteristics of the read sensors 108A and 108B, and have light sourcelight (light source light amount, light source wavelength range)adjusted in correspondence with the light-receiving elements of the readsensors 108A and 108B. FIG. 7 shows the layout of the document, imageread sensors 108A and 108B, lens arrays 109A and 109B, andlight-emitting element arrays 110A and 110B.

[0059]FIG. 5 is a schematic perspective view showing principal part ofthe image reading apparatus. A photographing unit will be explainedbelow using FIGS. 1 and 5.

[0060] Reference numerals 111A and 111B denote transparent MF guideglass windows which are provided on the convey path to take a photo ofthe conveyed document 101; and 112A and 112B, cold cathode tube typeillumination lamps serving as a second image illumination unit whichilluminates the document to project an image onto a microfilm.

[0061] The illumination lamps 112A and 112B can be set as light sourcesaccording to the light-receiving sensitivity characteristics of themicrofilm, and have light source light (light source light amount, lightsource wavelength range) adjusted to the microfilm. For example, ahalogen lamp or a cold cathode lamp of white or single color is used.

[0062] Reference numerals 113A and 113B denote first mirrors which forman optical path for projecting an image of the illuminated document ontothe microfilm; and 114, a variable slit which can adjust the amount oflight that exposes the microfilm. This light amount varying mechanismcan change the optical path width of the optical path projected onto themicrofilm, as shown in FIG. 4.

[0063] Reference numerals 115, 116, and 117 denote second, third, andfourth mirrors for guiding the optical path adjusted by the slit 114toward the microfilm side; and 118, a microfilm lens for forming anoptical path that projects an image onto the microfilm. Referencenumeral 119 denotes a microfilm as one of photosensitive materials. Notethat the second mirror 115 in FIG. 5 is illustrated in a partiallycutaway state in its longitudinal direction, so that the state of theslit 114 is easy to see.

[0064] The operation of the apparatus will be briefly explained below.The document 101 serving as an object is separated and fed one by onefrom a stack of a plurality of documents by the pickup roller 102, feedroller 103, and separation roller 104. The fed document 101 is fed intothe guide glass windows 107A and 107B and is conveyed to the readposition of the read sensors 108A and 108B by the convey rollers.

[0065] The document 101 that has reached a desired position isilluminated by the light-emitting element arrays 110A and 110B, and itsimage is read by the read sensors 108A and 108B via the lens arrays 109Aand 109B. After sensitivity adjustment of the light-receiving elementsand photoelectric conversion of received image data in accordance withexternal commands, segmentation to predetermined levels is done. In thisway, density adjustment and contrast setting upon reading an image canbe done, thus obtaining a desired image.

[0066] Since the read sensors 108A and 108B, lens arrays 109A and 109B,and LED (light-emitting element) arrays 111A and 110B are arranged onthe upper and lower sides of the document convey path in FIG. 1, theobverse and reverse sides of the document can be read.

[0067] Since the light-emitting element arrays are constructed to beable to selectively emit lights of plural wave lengths for dealing acolor document, it is able to skip the reading of an arbitrary color orto emphasize an arbitrary color. Further, it is able to read thedocument with color.

[0068] The document, images of which have been read by the read sensors108A and 108B, is conveyed to the MF guide glass windows by the conveyrollers 105 while being held by the convey guide plates 106A and 106B.The conveyed document 101 is illuminated by the cold cathode tube typeillumination lamps 112A and 112B. As can be seen from FIG. 3, since theread sensors 108A and 108B, and the microfilm 119 have differentsensitivity characteristics, the lamps 112A and 112B can provide lightsource light suitable for the microfilm 119.

[0069] An image on the illuminated document 101 is guided to thevariable slit 114 via the first mirrors 113A and 113B, and is adjustedby the variable slit 114 to a predetermined light amount. The adjustedimage then exposes the microfilm 119 via the second, third, and fourthmirrors 115, 116, and 117. FIG. 4 schematically depicts the light amountvarying operation by the variable slit 114.

[0070] After the microfilm 119 is exposed, the document is exhausted viaan exhaust port (not shown) by the convey rollers 105 while being heldby the convey guide plates 106A and 106B.

[0071] The series of operations are done at each speed corresponding tothe read resolution of the light-receiving elements.

[0072] Since the light source used upon reading an image, and that usedupon exposing the microfilm are independently arranged, the lightsources can be set in correspondence with their photosensitivecharacteristics. Hence, the read image is free from any deterioration(e.g., blurred text, fog, or the like) due to a filter or the like.Since the light source corresponding to the sensitivity characteristicsof the microfilm can be used upon photographing using the microfilm, ahigher-quality image with high contrast can be obtained. Further, astable reading of an image is accomplished by changing and setting thelight source according to a color document.

[0073] Since the illumination units are independently arranged, moreappropriate, flexible setups can be made in correspondence with thedocument convey speed.

[0074] As described above, according to the first embodiment, since theapparatus comprises the first image illumination unit for illuminatingthe document to be read by the image reading unit, and the second imageillumination unit for illuminating the document to be recorded by thephotographing unit, the light sources can be set in correspondence withthe photosensitive characteristics of the image reading unit andphotographing unit, respectively.

[0075] More specifically, the read image is free from any deterioration(e.g., blurred text, fog, or the like) due to a filter or the like. Uponphotographing using a photosensitive material, since the light sourcecorresponding to the sensitivity characteristics of the photosensitivematerial can be used, higher-quality image with high contrast can beobtained. Since the illumination units are independently arranged, moreappropriate, flexible setups can be made in correspondence with thedocument convey speed.

[0076] (Second Embodiment)

[0077] The second embodiment of an image reading apparatus according tothe present invention will be described below with reference to theaccompanying drawings. Note that the shapes of building components,their relative layout, and the like described in this embodiment do notlimit the scope of the present invention to themselves unless otherwisespecified. Also, numerical values are presented for the referencepurpose, and do not limit the scope of the present invention tothemselves.

[0078] FIGS. 8 to 12 show an image reading apparatus of the secondembodiment. FIG. 8 is a schematic front sectional view of an imagereading apparatus 501. The image reading apparatus 501 comprises adocument feed unit 503, image reading unit 520, document conveying unit518, microfilm photographing unit (photographing unit) 527, controlcircuit (control unit) 560 for controlling the overall image readingapparatus 501, console panel (resolution selector, density setter,obverse/reverse selector) 558, and the like.

[0079] In the document feed unit 503, when a document 507 is placed on apaper feed tray 506 of a main body 502 of the image reading apparatus501, the paper feed tray 506 moves upward to urge the document 507against a pickup roller 505 under the control of the control circuit560. The document 507 then moves in the direction of an arrow A uponrotation of the pickup roller 505. The document 507 is separated andconveyed one by one by a feed roller 509 and separation roller 510,which rotate in the directions of arrows in FIG. 8, and is fed into theapparatus main body 502. The pickup roller 505, feed roller 509, andseparation roller 510 are respectively rotated by motors 561, 562, and563.

[0080] The document 507 that has been separated and fed is conveyedinside the apparatus main body 502 by pairs of rollers 511, 512, 513,514, 515, 516, 517, and 532, which are rotated by a driving motor 564,and is exhausted onto an exhaust tray 534. Rotations of the motors 561,562, 563, and 564 are controlled by the control circuit 560 to be ableto change the convey speed of the document. The driving motor 564 andthe pairs of rollers 511, 512, 513, 514, 515, 516, 517, and 532constitute the document convey unit 518.

[0081] Image reading units 521 and 522 which form the image reading unit520 respectively include dedicated illumination light sources andphotoelectric conversion elements, and convert document images intoimage information data in response to a control signal from the controlcircuit 560. The image reading units 521 and 522 are arranged along theconvey path to respectively face the obverse and reverse sides of thedocument, and convert images on the two sides of the document into imageinformation data by conveying the document only once.

[0082] The image resolution of the image reading units 521 and 522 ischanged by changing the speed of the convey motor 564 which rotatesunder the control of the control circuit 560. The image resolution isselected and input by the user at the console panel 558.

[0083] A pair of opposed document guide glasses 504 are disposed on thedocument convey path. The document 507 which passes the document guideglasses 504 is illuminated by illumination lamp units 523 and 524 viathese document guide glasses. At this time, light scattered by thedocument 507 is guided into an optical path and exposes a microfilm F(see FIG. 9), thus taking a photo.

[0084] In this manner, the document 507, the image information of whichhas been read and which has undergone microfilm photographing, isexhausted from an exit 533 onto the exhaust tray 534 via a pair of exitrollers 532.

[0085]FIG. 9 is a perspective view showing one aspect of an opticalsystem of the microfilm photographing unit 527 according to the presentinvention.

[0086] Light components scattered by the document 507, the obverse andreverse surfaces of which are illuminated by the illumination lamp units523 and 524 within the region of the document guide glasses 504, arereflected by first mirrors 537 a and 537 b, pass through exposureadjustment slits (slits) 538 and 539, are reflected obliquely downwardby a second mirror 540, and are then reflected upward by a third mirror541. After that, the scattered light components are reflected forward bya fourth mirror 542, are transmitted through an imaging lens 543 of amicrofilm camera 544, and form an image on a microfilm F as a recordingmedium on a capstan 545.

[0087] The capstan 545 is coupled to a driving system of the main body502 of the image reading apparatus 501 via a capstan clutch (not shown).The capstan clutch is coupled in synchronism with the timing at whichthe document 507 reaches the photographing position. When the capstanclutch is coupled, the capstan 545 is rotated by the driving system toconvey the microfilm F. The moving amount and remaining amount of themicrofilm F are detected by an encoder as a detector (not shown), whichis coupled to the capstan 545.

[0088] The microfilm camera 544 is detachably attached to the main body502 of the image reading apparatus 501. The microfilm camera 544 has theimaging lens 543 corresponding to the photographing magnification of themicrofilm, the capstan 545, and a reduction gear for driving the capstan545 at a reduction gear ratio corresponding to the document convey speedof the main body 502 of the image reading apparatus 501.

[0089] In FIG. 8, lamp light amount sensors 525 and 526 detectvariations of amounts of light emitted by the illumination lamp units523 and 524.

[0090]FIG. 10 is a perspective view of the exposure adjustment slitmechanism (exposure adjustment unit) 549 in the microfilm photographingunit 527. Cutaway portions in FIG. 10 indicate omissions in thelongitudinal direction. The exposure adjustment slit mechanism 549comprises a stationary frame 550, slit plates (adjustment members) 551and 552, slit driving motors 553 and 554, home position sensors 556 and557, and the like. The slit plates 551 and 552 are respectivelyconnected to the slit driving motors 553 and 554. The open/close amountsof exposure adjustment slits 538 and 539 are adjusted by driving theslit driving motors 553 and 554. The slit driving motors 553 and 554 usepulse motors or the like since they control the moving amounts of theslit plates 551 and 552, although their types are not particularlylimited.

[0091] The slit plates 551 and 552 which change the widths of theexposure adjustment slits 538 and 539 upon driving of the slit drivingmotors 553 and 554 move in the same direction as the document conveydirection when the exposure adjustment slits 538 and 539 are opened.

[0092] The home position sensors 556 and 557 detect if the slit plates551 and 552 are located at home positions as their downward positions.The home position sensors 556 and 557 output home position signals whenthe exposure adjustment slits 538 and 539 are completely closed. Withthis arrangement, upon detecting the home positions of the slit plates551 and 552, the exposure adjustment slits 538 and 539 need not beopened, thus preventing the microfilm F from being irradiated with extralight.

[0093] The operation of the exposure adjustment slit mechanism 549 willbe explained below.

[0094] When the document 507 has passed a document sensor 508 disposedupstream the document guide glasses 504 in FIG. 8, the control circuit560 calculates the widths of the exposure adjustment slits 538 and 539that give appropriate exposure to the microfilm F on the basis of thedocument convey speed, and controls driving of the obverse and reverseslit driving motors 553 and 554, thus opening the exposure adjustmentslits 538 and 539.

[0095] The opening/closing timings of the exposure adjustment slits 538and 539 by the slit plates 551 and 552 change depending on the documentspeed and open/close amounts, and the movement end timing of the slitplates 551 and 552 to appropriate slit widths preferably matches thearrival timing of the leading end of the document to the document guideglasses 504. That is, when the document convey speed is high, and theopen/close amounts of the exposure adjustment slits 538 and 539 arelarge, the slit plates 551 and 552 must move upward relatively earlyafter the document 507 has passed the document sensor 508. On the otherhand, when the document convey speed is low and the open/close amountsof the slits are small, the slit plates 551 and 552 must move upward agiven time after the document has passed the document sensor.

[0096] In this way, when the document convey speed is low, the slitplates begin to operate at the same timing as that for high documentconvey speed after the document has passed the document sensor 508, thuspreventing wasteful exposure.

[0097] In the open/close amount control of the exposure adjustment slits538 and 539, since the open/close amounts are finely adjusted incorrespondence with light amount signals from the lamp light amountsensors 525 and 526, a light amount change circuit of a lamp controlcircuit, which is required in the conventional apparatus, can beremoved, and microfilm exposure can be adjusted by a simple circuitarrangement.

[0098] In a duplex mode in which the two surfaces of the document aresimultaneously photographed, the open/close amounts of the exposureadjustment slits 538 and 539 are finely adjusted in accordance with thelight amounts of the obverse and reverse illumination lamp units 523 and524.

[0099] The illumination lamp units 523 and 524 are turned on at anearlier timing than the open/close start timing of the exposureadjustment slits 538 and 539.

[0100] After the light amounts of the illumination lamp units 523 and524 become stable, the slit plates 551 and 552 can move to the slitwidths, which are calculated on the basis of the detected light amountsof the illumination lamp units 523 and 524, the document convey speed,and the density input by the user at the control panel 558, at a timingbefore the leading end of the document reaches the document guideglasses 504.

[0101] For this reason, when the illumination lamp units 523 and 524require a certain time until their light amounts become stable, they maybe turned on before a document is fed from the paper feed tray 506.

[0102] When the leading end of the document has reached the documentguide glasses 504 after the exposure adjustment slits 538 and 539 areopened/closed by an appropriate amount, the capstan 545 that conveys themicrofilm F is coupled to the driving system (not shown) provided to themain body 502 via the clutch (not shown) and conveys the microfilm F ata speed corresponding to the document convey speed and photographingmagnification. In this way, the document image is photographed on themicrofilm F.

[0103] When the trailing end of the document has passed the documentguide glasses 504, the control circuit 560 drives the obverse andreverse slit driving motors 553 and 554 in the reverse direction untilthe slit plates 551 and 552 are detected by the home position sensors556 and 557, thus closing the exposure adjustment slits 538 and 539.After the exposure adjustment slits 538 and 539 are completely closed,clutch connection (not shown) is released, and conveyance of themicrofilm F is stopped, thus ending photographing.

[0104] In the above operations, when the read resolution of the imagereading unit 520 is changed, the slit widths of the microfilmphotographing unit also change to adjust the exposure value of themicrofilm. At this time, when the image is read at a high resolution,the document convey speed becomes low, and the widths of the exposureadjustment slits 538 and 539 decrease. In slit exposure of themicrofilm, a microfilm photographed image has higher resolution withdecreasing widths of the exposure adjustment slits 538 and 539.Conversely, when the image reading unit 520 reads an image at a lowresolution, the document convey speed becomes high, the slit widthsbecome large, and the photographing resolution of the microfilm alsobecomes low. Therefore, since the resolution of the microfilmphotographed image increases in correspondence with the operation forincreasing the image read resolution, operations can be standardized,and the read image information and microfilm image as a backup can havecorrelation.

[0105] According to the image reading apparatus 501 of the presentinvention, even when a simple lamp control circuit is used, microfilmphotographing can be simultaneously made without sacrificing theperformance of the image reading unit 520. In addition, neither anexpensive photoelectric conversion element nor image processing circuitare required, and an inexpensive apparatus can be provided.

[0106] Furthermore, the image reading apparatus 501 can take correlationbetween the read image information and the resolution of the microfilm,which is effective upon searching and relating microfilm images usingthe read image information and vice versa.

[0107]FIG. 11 shows an optical path at a high document convey speed.

[0108] When the document convey speed is high, since the convey speed ofthe microfilm F is also high, exposure to the microfilm F must beincreased. Therefore, the widths of the exposure adjustment slits 538and 539 are set large. For this reason, an effective exposure region tothe microfilm F has a width indicated by symbol a at the position of thedocument guide glasses 504.

[0109] If the exposure adjustment slits 538 and 539 are opened/closedwhile the document is located within the effective exposure region a atthe position of the document guide glasses 504, density nonuniformity isgenerated on the microfilm F and, hence, the exposure adjustment slits538 and 539 cannot be opened/closed. Therefore, the close start timingof the slits is set when the trailing end of the document has passed theeffective exposure region a.

[0110]FIG. 12 shows an optical path at a low document convey speed.

[0111] When the document convey speed is low, since the convey speed ofthe microfilm is also low, exposure to the microfilm must be decreased.Therefore, the widths of the exposure adjustment slits 538 and 539 areset small. For this reason, the effective exposure region to themicrofilm F has a width indicated by symbol b at the position of thedocument guide glasses 504.

[0112] When the document convey speed is high, the effective exposureregion near the document guide glasses 504 is smaller than that at a lowdocument convey speed.

[0113] For example, when the effective exposure region has a width of 2mm at 600 dpi, a high-speed convey state at 100 dpi requires a conveyspeed six times that at 600 dpi, and an effective exposure region of 12mm is required. In this way, the effective exposure regions at 600 and100 dpi have a difference of 10 mm on the conveyed document, and aregreatly effective upon photographing and saving a small check,certificate, and the like.

[0114] By changing the close timings of the exposure adjustment slits538 and 539 and the convey stop timing of the microfilm incorrespondence with a change in trailing end of the effective exposureregion depending on the document convey speed, film consumption perimage of the microfilm can be reduced.

[0115] In the duplex mode in which the two surfaces of the document aresimultaneously photographed, since the widths of the exposure adjustmentslits 538 and 539 are finely adjusted in correspondence with the amountsof light of the obverse and reverse illumination lamp units 523 and 524,the obverse and reverse effective exposure regions have differentwidths. At this time, the widths of the exposure adjustment slits 538and 539 are compared, and the convey stop timing of the microfilm ischanged to the close timing of the exposure adjustment slit with thelarger width.

[0116] According to this embodiment, the frame spacing on the microfilmcan be minimized. However, when the document skews upon conveying, animage loss occurs.

[0117] By contrast, when a skew of the document is detected upon readingan image by the image reading units 521 and 522 before microfilmphotographing, the control is switched to broaden the frame spacing onthe microfilm without closing the exposure adjustment slits 538 and 539and stopping conveyance of the microfilm irrespective of the documentconvey speed until the document is conveyed a sufficiently largedistance after it has passed the effective exposure region. In this way,even when the document skews, an image loss on the microfilm can beprevented.

[0118] Upon photographing only one surface of the microfilm (to be alsoreferred to as a simplex mode), the control circuit 560 maintains theillumination lamp unit 523 (or 524) on the non-photographing side OFF,and also the exposure adjustment slit on the non-photographing sideclosed. The user can select on the control panel 558 one or both thesurfaces (obverse and reverse surfaces) of the document, which to beread and photographed.

[0119] In this manner, since the illumination lamp unit 523 (or 524) onthe non-photographing side is not turned on if no slit plate which isrequired in the microfilm photographing unit 527 having the simplexphotographing mode is inserted, halation due to light rays from thenon-photographing side, fog due to the illumination lamp on thephotographing side, which is transmitted through the document, and thelike can be prevented. One cause of fog is photographing usingbacklight.

[0120] When operation errors such as jam and the like have occurred inthe apparatus, they are detected by sensors (abnormality detectors) 571,572, 573, and 574, and the control circuit 560 forcibly closes theexposure adjustment slits 538 and 539 and turns off the illuminationlamp units 523 and 524 irrespective of the presence/absence of adocument.

[0121] Furthermore, when an abnormality has occurred, entrance ofexternal light rays into the microfilm photographing optical path uponremoving a document that is stuck in the document convey portion by theuser can be prevented.

[0122] (Third Embodiment)

[0123] A microfilm photographing unit 627 which operates when thedocument convey spacing is small or when the slit driving motors 553 and554 operate at low speed will be explained below with reference to FIG.13. The same reference numerals denote the same parts as in the secondembodiment, and a description of the structure and operations of thoseparts will be omitted.

[0124] When the document spacing is small or when the slit drivingmotors 553 and 554 operate at low speed, it becomes impossible tocompletely control to open/close the exposure adjustment slits 538 and539 at the document spacing, as described in the second embodiment.

[0125] For this reason, the illumination lamp units 523 and 524 areturned on simultaneously with the beginning of document conveyance, andthe slit driving motors 553 and 554 are then controlled in accordancewith the outputs from lamp light amount sensors (sensors correspondingto reference numerals 525 and 526 in FIG. 8) and the document conveyspeed, thus adjusting the exposure adjustment slits 538 and 539 topredetermined widths.

[0126] When a document sensor 547 arranged upstream the document guideglasses 504 detects the document after the exposure adjustment slits 538and 539 are adjusted, the control circuit releases a shutter(light-shielding portion) 546 inserted before the lens 543 by actuatinga plunger (light-shielding portion) 548 at the same timing as that whenthe leading end of the document reaches the document guide glasses 504,and starts conveyance of the microfilm F at the same time. Note that theplunger 548 may work based on the document convey speed without usingany sensor.

[0127] Then, when the trailing end of the document has passed theeffective exposure region on the document guide glasses 504 calculatedfrom the widths of the exposure adjustment slits 538 and 539, thecontrol circuit closes the shutter 546, and stops the conveyance of themicrofilm.

[0128] After the document has completely left the document guide glasses504, the control circuit finely adjusts the exposure adjustment slitsagain on the basis of the outputs from the lamp light amount sensors.

[0129] The reason why the exposure adjustment slits 538 and 539 are notfinely adjusted while the document is located at the position of thedocument guide glasses 504 is as follows. That is, since light comingfrom the illumination lamp units 523 and 524 is irregularly reflected bythe document surface and the outputs from the lamp light amount sensors525 and 526 fluctuate (especially, sensor outputs readily changedepending on the document density), accurate lamp light amount outputscannot be obtained.

[0130] Also, the reason why the widths of the exposure adjustment slits538 and 539 are not controlled while the document is located at theposition of the document guide glasses 504 is that when a change inimage density due to a change in slit width per step of the slit drivingmotors 553 and 554 occurs within a single image, it appears as imagenonuniformity. Furthermore, such image nonuniformity within a singleimage cannot be corrected and remains as nonuniformity on an outputimage when that image is printed out by a microfilm reader/printer (notshown) after photographing.

[0131] By contrast, when images have slight density differences, if eachimage undergoes automatic density correction of the reader/printer, suchdifferences can be eliminated. By repeating the above operations duringconveyance of the document, a change in light amount of the illuminationlamp units 523 and 524 can be coped with.

[0132] After the entire effective photographing region of the documenthas passed, the exposure adjustment slits 538 and 539 are closed, theillumination lamp units 523 and 524 are turned off, and conveyance ofthe microfilm is stopped, thus ending all processes.

[0133] In this way, when the widths of the exposure adjustment slits 538and 539 are changed between only documents, exposure to the microfilmcan be appropriately adjusted in correspondence with variations of lamplight amounts, and the feed interval of documents can be shortened evenwhen slow, inexpensive motors are used, thus improving the overallprocessing performance of the apparatus.

[0134] Therefore, since the image reading apparatus having the microfilmphotographing unit 527 or 627 of the above embodiment changes the readresolution of the document scanner and the photographing resolution ofthe microfilm at the same time, the resolution of the document scannercan change in correspondence with the photographing resolution of themicrofilm, and correlation between saved digital data and imagesphotographed on the microfilm can be easily taken. Since the imagereading apparatus of this embodiment changes the slit widths of themicrofilm photographing unit in accordance with the document conveyspeed, the read resolution can be freely changed by adjusting exposureto the microfilm without changing the light amounts of the illuminationlamp units. Hence, the document scanner can have a compact, inexpensivearrangement.

[0135] Furthermore, since the lamp light amount sensors are added, andthe slit widths are changed in consideration of the lamp service life, achange in light amount of the lamps due to temperature, and the like,the need for a light amount varying circuit in the lamp light amountcontrol circuit can be obviated. Hence, the apparatus arrangement can besimplified, and a cost reduction can be achieved.

[0136] In the conventional microfilm photographing apparatus, when onlyone surface of a document is to be photographed, a light-shieldingshutter is provided to the non-photographing side to avoid abnormalexposure due to light which comes from the illumination lamp on thephotographing side and is transmitted through, e.g., a thin document.However, the arrangement of this embodiment can obtain the same effectby closing the exposure adjustment slit without any light-shieldingshutter.

[0137] Furthermore, when the document convey speed is low, thephotographing frame spacing on the microfilm can be reduced inconsideration of the widths of the exposure adjustment slits, and alarger number of images can be photographed on a microfilm if its lengthremains the same.

[0138] When an abnormality has occurred in the apparatus duringmicrofilm photographing, the slits are closed. In this way, even whenthe document convey path is opened upon removing a document that isstuck inside the apparatus, abnormal incoming light can be preventedfrom entering the microfilm photographing optical path without addingany new parts.

[0139] Since the image reading apparatus of the second and thirdembodiments can adjust exposure in correspondence with the documentconvey speed by controlling the degree of opening of each slit of theexposure adjustment unit even when the document read speed has changed,an image can be reliably read and photographed by a simple structure.

[0140] The present invention is not limited to the above embodiments andvarious changes and modifications can be made within the spirit andscope of the present invention. Therefore, to apprise the public of thescope of the present invention the following claims are made.

What is claimed is:
 1. An image reading apparatus which comprises: animage reading unit which reads image information of a document; and aphotographing unit which records an image of the document on aphotosensitive material by exposure, said apparatus further comprising:a first image illumination unit which illuminates the document read bysaid image reading unit; and a second image illumination unit whichilluminates the document recorded by said photographing unit.
 2. Theapparatus according to claim 1, wherein said image reading unitcomprises a light-receiving element for photoelectrically convertinglight reflected by the document, which is illuminated by said firstimage illumination unit, said first image illumination unit can be setas a light source according to photosensitive characteristics of saidlight-receiving element, and said second image illumination unit can beset as a light source according to photosensitive characteristics of thephotosensitive material.
 3. The apparatus according to claim 1, whereinsaid first and second image illumination units have differentillumination light amounts.
 4. The apparatus according to claim 1,wherein said first and second image illumination units use illuminationlight beams having different wavelengths.
 5. The apparatus according toclaim 1, wherein said first and second image illumination units canindependently set light source light amounts.
 6. The apparatus accordingto claim 1, wherein said first and second image illumination units canchange a wavelengths of emitting lights.
 7. The apparatus according toclaim 1, wherein at least one of said first and second imageillumination units comprises a light amount varying mechanism for makinglight amount adjustment.
 8. The apparatus according to claim 1, whereinsaid first and second image illumination units have different forms. 9.The apparatus according to claim 1, wherein said second imageillumination unit comprises a cold cathode tube having a monochromelight source.
 10. The apparatus according to claim 1, wherein at leastone of said first and second image illumination units makes light amountadjustment in accordance with a convey speed of the document read bysaid image reading unit or recorded by said photographing unit.
 11. Animage reading apparatus comprising: a document convey unit which conveysa document; an image reading unit which reads an image on the documentconveyed by said document convey unit; a resolution selection unit whichselects an image read resolution of said image reading unit; aphotographing unit which has an exposure adjustment unit which adjustsan exposure value by controlling a degree of opening of a slit, andphotographs an image on the document conveyed by said document conveyunit; and a control unit which controls operations of said documentconvey unit and said exposure adjustment unit on the basis of theresolution selected by said resolution selection unit so as to adjust aconvey speed of the document and the exposure value.
 12. The apparatusaccording to claim 11, further comprising an illumination unit whichilluminates the document, a light amount detection unit which detects alight amount of said illumination unit, and a density setting unit whichsets a photographing density of said photographing unit, and whereinsaid control unit controls an operation of said exposure adjustment uniton the basis of the convey speed of the document and the density set bysaid density setting unit so as to adjust the exposure value.
 13. Theapparatus according to claim 11, wherein when said control unit controlssaid document convey unit to decrease the document convey speed andcontrols said exposure adjustment unit to decrease the exposure value,said control unit controls said photographing unit to reduce aphotographing frame spacing.
 14. The apparatus according to claim 11,wherein said photographing unit has a pair of exposure adjustment unitscorresponding to two surfaces of the document, and can photograph thetwo surfaces of the document.
 15. The apparatus according to claim 11,further comprising an obverse/reverse selection unit which selects oneof two surfaces of the document, which is to be photographed, andwherein said control unit controls an operation of only the exposureadjustment unit corresponding to the surface selected by saidobverse/reverse selection unit.
 16. The apparatus according to claim 11,further comprising an abnormal detection unit which detects an operationabnormal state of said apparatus, and wherein said control unit controlssaid exposure adjustment unit to shield light when said abnormaldetection unit detects an abnormal state.
 17. The apparatus according toclaim 11, further comprising a light-shielding unit which shields lightto said photographing unit, and wherein light to said photographing unitis shielded by operating said light-shielding unit.
 18. The apparatusaccording to claim 11, wherein said exposure adjustment unit has anadjustment member which adjusts the degree of opening of the slitthrough which light reflected by the document passes, and said controlunit operates said adjustment member to adjust the degree of opening ofthe slit so as to adjust the exposure value.
 19. The apparatus accordingto claim 14, wherein when slits of the pair of exposure adjustment unitshave different degrees of opening, said control unit sets aphotographing spacing of said photographing unit on the basis of thelarger degree of opening.